(Above) Although Flying Scotsman has been out of action since it was withdrawn from mainline operations in 2006, the NRM’s promise of the best possible care for maximum public exposure is still at the heart of all of its intentions.

In 2004 one of the most iconic steam locomotives in the world was saved for the nation when the National Railway Museum in York acquired locomotive No. 4472 Flying Scotsman.

The £2 million coup – backed by a fervent public appeal and a large grant from the National Heritage Memorial Fund – meant the famous green steam engine was brought to the world’s largest railway museum adjacent to its old stamping ground, the East Coast main line.

Since then the intention has been to get the Scotsman running again to ensure as many people as possible can enjoy the spectacle of it steaming across the country. In fact the NRM bought Flying Scotsman under the promise that it would be given the best possible care in order for it to be enjoyed on the main line for many years to come.

A new campaign was launched a year ago to raise the necessary £250,000 to get the Scotsman repaired and flying again. The total money raised currently stands at £140,000 and the NRM is this week revealing the extent of the meticulous restoration work needed to get the great loco back on the tracks.

"Flying Scotsman has been in more or less continuous operation since it was built in 1923, having been overhauled and operated in preservation since its withdrawal from BR service in 1962," says Helen Ashby, NRM Head of Knowledge & Collections.

"This means that many of the components are now extremely worn and much more has had to be refurbished or replaced than is usually the case with a ten year overhaul."

As a result the entire locomotive has in fact been disassembled and every little piece examined to see if it needs replacing. As well as being expensive, it’s clearly a complicated process. Ashby says the Scotsman "could have been back on the mainline a couple of years ago" but would have probably been "back in the workshop by now".

“When we took Flying Scotsman off the mainline for restoration, we made the decision to do it properly,” she says. “This may have proven to be a long and challenging process, but the end result will be that Flying Scotsman will be able to operate on the mainline for the public to enjoy for the next two or three decades.”

Work is due to be completed on the Flying Scotsman in summer 2011. Photo Courtesy NRM

The restoration programme, which has been devised by the NRM's new Engineering and Rail Operations Manager, Chris Beet, should see Flying Scotsman back operating on the mainline in the summer of 2011.

Staff have been consulting the NRM's research and archive facility, Search Engine, to find engineering drawings of an A3 locomotive from the 1940s from which new components are carefully manufactured.

"This process is the same for nearly every component on the locomotive," says Beet, "it’s this level of detail that makes the process so long winded. But it is also this level of detail that ensures we are giving Flying Scotsman the quality restoration she deserves."

So there is much more work to be done before the most famous locomotive in the world is up and steaming again. Vacuum brakes enabling the Scotsman to safely travel across the myriad heritage railway lines in the UK are due to be fitted in spring 2010 and the chassis will be complete by autumn.

In spring 2011 the reconditioned boiler and chassis will be reunited in the NRM workshop and steam tests will begin shortly after. A return to the mainline is scheduled for Summer 2011.

Discussions are underway with operating partners and a schedule for Flying Scotsman's first season on the mainline will be released as soon as they are finalised. Given the engine's status amongst steam buffs and general public alike it’s going to be one of the most eagerly anticipated railway timetables in some years.